The invention relates to display devices.
High definition, multicolor display, low power consumption, lower voltage requirements and light weight have made liquid crystal displays (LCDs) a leading display device technology. LCDs have been used for several years as mobile information displays in, for example, personal digital assistants (PDAs), portable computers, mobile phones, and the like.
Recently, complementary metal oxide semiconductor (CMOS) shift register circuits have been widely applied in low-temperature poly-silicon (LTPS) LCDs. However, at least eight masks typically are required to form a CMOS shift register circuit during fabrication, and thus, costs are increased. For cost reduction, positive metal-oxide semiconductor (PMOS) shift registers, which require fewer masks, are used frequency by LCD makers.
FIG. 1 shows a conventional signal driving circuit comprising PMOS shift registers. As shown, the signal driving circuit 100 in the panel 10 requires four clock signals provided by an external integrated circuit (IC) to driving the PMOS shift registers via four FPC pins, and four sampling and holding units (L/S) to sample and hold the four clock signals. Because of the increased sampling and holding units (S/L), the power consumption and chip (layout) area are increased no matter they are integrated to the IC or the display panel, and thus cost is increased. Further, due to increase in FPC pins, contact reliability between the IC and panel by FPC becomes an important issue.